Advancing a filter mat in a roll filter



A ril 15, 1969 G. STEINHOLTZ ET AL ADVANCING A FILTER MAT IN A ROLL FILTER Filed Jan. 50, 1967 INVENTORS cbsrA STEINHOLTZ BO ARONSSON BY W4 ATTYS- United States Patent Office 3,438,588 Patented Apr. 15, 1969 US. Cl. 24255.1 2 Claims ABSTRACT OF THE DISCLOSURE A roll filter wherein a filter mat is advanced from a freely rotatable supply roll onto a take-up roll, which is driven with a constant angular speed so as to gradually increase the peripheral speed of the mat to a maximum peripheral speed as the diameter of the take-up roll increases. The m-at is guided in a zigzag path intermediate the supply and take-up rolls by two rows of guide rolls one of which rows is freely rotatable and the other of which rows is driven so that the rolls have a constant peripheral speed at least as great as the maximum peripheral speed of the take-up roll. When the mat is frictionally engaged with the driven guide rolls, these rolls create a slack in the mat between the guide rolls and the take-up rolls. When the slack is sufficient, the frictional engagement on the driven guide rolls is relieved and the driven guide rolls no longer drive the mat. The continuously driven take-up roll takes up the slack to thereby reinstate the frictional engagement of the mat on the driven guide rolls so that the mat is alternately slackened and ten sioned as it is advanced through the filter.

The present invention relates to advancing a filter mat in a roll filter whereby the mat is advanced from a supply roll at one side of the filter in a zigzag path through the filter around a number of guide rolls of the same size and operated at the same angular and peripheral speed and is thereafter wound up on a take-up roll at the other side of the filter from the supply roll.

In conventional roll filters, both the guide rolls and the winding or take-up roll are normally driven at constant peripheral speeds which are uniform throughout so that the mat is advanced by all of the rolls at the same speed as it is wound up on the take-up roll. Since the diameter of the mat on the take-up roll increases, the winding roll must thereby be operated by a slip clutch to provide a constant peripheral speed.

However, it has proved difiicult to provide a slip clutch which works satisfactorily and maintains a constant pulling force on the filter mat as the diameter of the take-up roll is changed. When the clutch fails to operate properly, tensile forces arise in the filter mat which are transmitted to the guide rolls and cause damage to the bearings and driving devices thereof.

A primary object of the present invention is to provide a reliable advancing of the filter mat under all running conditions.

Another object is to avoid the application of tension to the filter mat which will stress the guide rolls.

More particularly, the present invention contemplates advancing the filter mat by the use of a take-up roll which rotates at a constant angular speed and thereby increases the peripheral speed toward a maximum as the diameter of the take-up roll increases, and driving guide rolls at a constant angular speed which produces a constant peripheral speed at least as great as the said maximum peripheral speed.

The figure of the drawing illustrates an embodiment of a roll filter according to the invention is schematic section.

Referring to the illustrated embodiment, the filter mat -1 is wound up on a supply roll 2, from which it is advanced in a zigzag path by means of a number of guide rolls 3 and 4. The guide rolls 3 are running free, whereas the guide rolls 4 are driven by a motor 8 by way of an intermediate shaft 7 and two connecting rods 5 and cranks, one at each end of the guide rolls 4. The cranks for the connecting rods at the periphery of the guide rolls are displaced in relation to each other in order to eliminate the dead points. In this case the cranks form a center angle of As the mat 1 is used, it is rolled up on a take-up roll 6 which is driven by the motor 8.

In accordance with the invention, the take-up roll 6 is working with a constant angular speed, which means that the peripheral speed and consequently the rolling-up of the mat increases as the diameter of the roll 6 increases. When the roll is filled, the peripheral speed is thus at its maximum. Since the guide rolls 4 are driven by the connecting rods 5 at a constant angular speed, and since the diameters of the rolls 4 are uniform, the peripheral speeds of the rolls 4 will also be uniform.

In accordance with the invention, the driving connections to the guide rolls 4 are such that the peripheral speed of the rolls 4 are at least as great as the maximum peripheral speed of the take-up roll 6. The filter mat 1 is discharged to the take-up roll 6 over a free-running end roll 9 which is freely rotatable on the intermediate shaft 7. At one end, the intermediate shaft is provided with three fixedlyqmounted chain wheels or sprockets by which the motor 8 drives the take-up roll 6 and the guide rolls 4.

In operation of the filter in accordance with the present invention, the filter mat 1 is advanced through the filter after being threaded as shown in the figure. When the tension in the filter mat is sufiicient to effect frictional engagement of the mat with the driven guide rolls 4, these rolls drive the mat and advance it a small increment. Since the guide rolls are driven faster than the takeup roll '6, a slack is created in the mat starting adjacent the take-up roll 6. The slack in the mat relieves the tension which causes the frictional engagement of the mat on the guide rolls, and the frictional engagement is lost so as to interrupt the drive of the mat by the guide roll 4. The continuously rotating take-up roll 6 continues to operate and soon takes up the slack in the mat and reestablishes the tension which presses the mat into frictional engagement with the guide rolls 4. At this point, the whole procedure is repeated. The intervals during which the guide rolls 4 are advancing the mat are short and follow rapidly after each other, so that the advancing procedure, in spite of the intermittent nature thereof, has the character of a continuous advancing.

I claim:

1. In a roll filter having a filter mat, a supply roll at one side of said filter, a take-up roll at the other side of said filter, guide rolls intermediate said supply roll and said take-up roll to direct said mat in a zigzag path therebetween, said guide rolls being arranged in two spaced rows in staggered relation, said supply roll and the guide rolls in one of said rows being freely rotatable, and drive means for the guide rolls in the other of said rows to drive the same uniformly at a constant angular and peripheral speed, the improvement including constant speed drive means for said take-up roll to rotate the same with a constant angular speed providing a peripheral speed which increases to a maximum as the filter mat is wound up thereon, the peripheral speed of the guide rolls in said other row being at least as great as the said maximum peripheral speed of the take-up rolls whereby said guide rolls do not advance said mat when said mat is slack, but do advance the mat when said slack is taken-up.

3 2. A method for advancing a filter mat in a roll filter having a supply roll and a take-up roll, and a series of guide rolls arranged in staggered relation to guide said mat in a zigzag path between said supply roll and said take-up roll, comprising the steps of driving the take-up roll with a constant angular speed to take up the mat at a peripheral speed which increases in accordance with the diameter of the mat on the take-up roll to a maximum peripheral speed, and driving alternate guide rolls constantly with a uniform peripheral speed at least as great as said maximum peripheral speed, so that said mat is alternately tensioned by said take-up roll and slackened by the driven guide rolls.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 7/1964 France.

WILLIAM S. BURDEN, Primary Examiner.

US. Cl. X.R. 

